(1) Field of the Invention
The invention relates to methods and apparatuses for sound production using large volume plasmas wherein transient phenomena are reproduced without time lag or distortion because of the lack of inertia of the active medium. In addition, the frequency response is flat and free from resonances.
(2) Description of the Prior Art
Various sound production systems, or speakers, are known in the art and applicant knows of two massless diaphragm speakers. One of these uses an acetylene flame seeded with Na produced by melting glass to give a conducting path. Electrodes positioned in the flame introduce an audio modulated direct current. This system requires extremely high temperatures to obtain the ionization, and the lack of control over the heat distribution makes the system unacceptable for commercial use. Another system comprises an audio modulated microwave generator which produces a very small spherical plasma, bounded by a quartz cavity, which is positioned in an exponential form. This system is limited in frequency response and output energy because of the very small plasma size, and horn loading is necessary to give a reasonable output intensity.
Applicant is aware of the following listed prior art U.S. Pat. Nos. which do not appear to teach or even suggest the invention claimed herein: 2,403,990, Mason; 2,483,768, Hershberger; 2,836,033, Marrison; 3,230,506, Hellund; 3,286,226, Kearshey et al; 3,371,309, Rich.
Hershberger suggests a sound generator comprising an absorptive gas confined within an enclosure and which is irradiated by microwaves modulated at an audio frequency.
Rich discloses an acoustic wave generator which creates compressional waves in response to changes in temperature created by a current source.
Hellund shows a transducer for generating pulses in an electrically conducting liquid.
Mason reveals a spark gap transducer for generating acoustical waves.
Marrison shows a heat controlled acoustic wave system wherein heat is applied to, and extracted from, a confined fluid column to create oscillations in the fluid.
Kearshey et al discloses a spark-discharge sound system for use underwater.